| 1. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 2. |
- Pattaro, Cristian, et al.
(författare)
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Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways.
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| 3. |
- German, C, et al.
(författare)
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Hydrothermal impacts on trace element and isotope ocean biogeochemistry
- 2016
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Ingår i: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-503X .- 1471-2962. ; 374:2081
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Tidskriftsartikel (refereegranskat)abstract
- Hydrothermal activity occurs in all ocean basins, releasing high concentrations of key trace elements and isotopes (TEIs) into the oceans. Importantly, the calculated rate of entrainment of the entire ocean volume through turbulently mixing buoyant hydrothermal plumes is so vigorous as to be comparable to that of deep-ocean thermohaline circulation. Consequently, biogeochemical processes active within deep-ocean hydrothermal plumes have long been known to have the potential to impact global-scale biogeochemical cycles. More recently, new results from GEOTRACES have revealed that plumes rich in dissolved Fe, an important micronutrient that is limiting to productivity in some areas, are widespread above mid-ocean ridges and extend out into the deep-ocean interior. While Fe is only one element among the full suite of TEIs of interest to GEOTRACES, these preliminary results are important because they illustrate how inputs from seafloor venting might impact the global biogeochemical budgets of many other TEIs. To determine the global impact of seafloor venting, however, requires two key questions to be addressed: (i) What processes are active close to vent sites that regulate the initial high-temperature hydrothermal fluxes for the full suite of TEIs that are dispersed through non-buoyant hydrothermal plumes? (ii) How do those processes vary, globally, in response to changing geologic settings at the seafloor and/or the geochemistry of the overlying ocean water? In this paper, we review key findings from recent work in this realm, highlight a series of key hypotheses arising from that research and propose a series of new GEOTRACES modelling, section and process studies that could be implemented, nationally and internationally, to address these issues. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’.
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| 4. |
- Havenhand, Jonathan N., 1959, et al.
(författare)
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Ecological and functional consequences of coastal ocean acidification : Perspectives from the Baltic-Skagerrak System
- 2019
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 48:8, s. 831-854
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Forskningsöversikt (refereegranskat)abstract
- Ocean temperatures are rising; species are shifting poleward, and pH is falling (ocean acidification, OA). We summarise current understanding of OA in the brackish Baltic-Skagerrak System, focussing on the direct, indirect and interactive effects of OA with other anthropogenic drivers on marine biogeochemistry, organisms and ecosystems. Substantial recent advances reveal a pattern of stronger responses (positive or negative) of species than ecosystems, more positive responses at lower trophic levels and strong indirect interactions in food-webs. Common emergent themes were as follows: OA drives planktonic systems toward the microbial loop, reducing energy transfer to zooplankton and fish; and nutrient/food availability ameliorates negative impacts of OA. We identify several key areas for further research, notably the need for OA-relevant biogeochemical and ecosystem models, and understanding the ecological and evolutionary capacity of Baltic-Skagerrak ecosystems to respond to OA and other anthropogenic drivers.
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| 5. |
- Ulfsbo, Adam, 1985, et al.
(författare)
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Modelling organic alkalinity in the Baltic Sea using a Humic-Pitzer approach
- 2015
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 168, s. 18-26
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Tidskriftsartikel (refereegranskat)abstract
- Significant excess alkalinity, of the order of 30 μmol kg− 1 and attributed to dissolved organic matter, has recently been measured in the Baltic Sea. Chemical speciation modelling shows that the measured excess alkalinity is consistent with an organic alkalinity derived from dissolved organic carbon, assuming that this dissolved organic carbon consists entirely of terrestrial humic substances. The contribution of polydisperse material such as humic substances to titration alkalinity invalidates the assumptions on which the current definition of titration alkalinity is based. It is therefore concluded that alkalinity should currently not be one of the parameters used to characterise the CO2 system in organic-rich waters. The use of a simple relationship to estimate organic alkalinity from the dissolved organic carbon concentration is assessed for the limited Baltic Sea data set currently available.
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| 6. |
- Endres, Sonja, et al.
(författare)
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A New Perspective at the Ship-Air-Sea-Interface : The Environmental Impacts of Exhaust Gas Scrubber Discharge
- 2018
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Ingår i: Frontiers in Marine Science. - : FRONTIERS MEDIA SA. - 2296-7745. ; 5
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Forskningsöversikt (refereegranskat)abstract
- Shipping emissions are likely to increase significantly in the coming decades, alongside increasing emphasis on the sustainability and environmental impacts of the maritime transport sector. Exhaust gas cleaning systems ("scrubbers"), using seawater or fresh water as cleaning media for sulfur dioxide, are progressively used by shipping companies to comply with emissions regulations. Little is known about the chemical composition of the scrubber effluent and its ecological consequences for marine life and biogeochemical processes. If scrubbers become a central tool for atmospheric pollution reduction from shipping, modeling, and experimental studies will be necessary to determine the ecological and biogeochemical effects of scrubber wash water discharge on the marine environment. Furthermore, attention must be paid to the regulation and enforcement of environmental protection standards concerning scrubber use. Close collaboration between natural scientists and social scientists is crucial for progress toward sustainable shipping and protection of the marine environment.
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| 7. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Determination of pH in estuarine and brackish waters: Pitzer parameters for Tris buffers and dissociation constants for m-cresol purple at 298.15K
- 2017
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 195, s. 84-89
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 Elsevier B.V. Measurements of pH in seawater are important to determine the natural and anthropogenic trends in the oceans. Spectrophotometry or glass electrode potentiometry measurements of pH require calibration with help of buffers. One common buffer solution is the Tris/Tris·H + couple, which should be well characterised both experimentally and theoretically for optimum accuracy. Chemical speciation modelling in the complex seawater medium is best addressed with an ion interaction approach, with Pitzer equations being the most widely used. The published Pitzer coefficients for Tris and Tris·H + in artificial seawater are based on isopiestic measurements, which necessarily give strong weight to the third virial coefficient C for the key interaction between Tris·H + and chloride. However, in low salinity waters it is the second virial coefficient B that is of greater importance. We have used Harned cell measurements of Tris solutions at ionic strengths up to 1molkg -1 to reassess the relevant Pitzer parameters, and have found improved agreement with experimental measurements in artificial seawater. We suggest that additional measurements should be undertaken to address the remaining differences between model calculations and experimental data in artificial seawater. We have used the revised Pitzer parameters to reassess the acid-base constant of the indicator m-cresol purple in low salinity waters.
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| 8. |
- Illuminati, S., et al.
(författare)
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In-situ trace metal (Cd, Pb, Cu) speciation along the Po River plume (Northern Adriatic Sea) using submersible systems
- 2019
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 212, s. 47-63
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Tidskriftsartikel (refereegranskat)abstract
- Information on the distribution and speciation of trace metals is of critical importance for our ability to interpret the links between the bioavailability and uptake of an element, and its biogeochemical cycle in coastal environments. Within the framework of the European Project "In-situ automated Monitoring of Trace metal speciation in Estuaries and Coastal zones in relation with the biogeochemical processes (IMTEC)", the chemical speciation of Cd, Pb and Cu was carried out along the Po River plume in the period 27 October - 2 November 2002. During the cruise, five Voltammetric In-situ Profiling systems and one Multi Physical Chemical Profiler, as well as conventional voltammetric instruments, were successfully applied in order to evaluate the distribution of Cd, Pb and Cu between different fractions (free ion, dynamic, colloidal, dissolved and particulate fractions) and to assess the evolution of these fractions during estuarine mixing and in the water column. Dynamic concentrations were 0.05-0.2 nmol L-1 Cd, 0.02-0.2 nmol L-1 Pb, and 0.15-4.0 nmol L-1 Cu. Cd was mainly present as dynamic fraction (40-100% of the dissolved Cd). High proportions of Pb (similar to 70%) and Cu (similar to 80%) were present as colloids probably of biogenic origin. Principal components analysis reveals a strong influence of the Po River discharge on the spatial and vertical distributions of metal species. Almost all the metal fractions globally decreased following the salinity gradient. Metal concentrations are far below (at least one order of magnitude lower) the Environmental Quality Standard established by the Italian law. However, the Cu dynamic fraction showed concentrations likely to be toxic to sensitive phytoplankton community and to have negative effects on larva development of coastal macroinvertebrate species (toxicity data extracted from literature).
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| 9. |
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| 10. |
- Turner, David R., 1951, et al.
(författare)
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Shipping and the environment: Smokestack emissions, scrubbers and unregulated oceanic consequences
- 2017
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Ingår i: Elementa. - : University of California Press. - 2325-1026. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- While shipping has long been recognised as a very carbon-efficient transport medium, there is an increasing focus on its broader environmental consequences. The International Maritime Organisation is responsible for the regulation of ship emissions arising from fuel combustion. Their current regulations are, however, much less strict than those applying to land-based transport within the European Union. Five different groups of pollutant emission from ship smokestacks are addressed in this paper: sulphur oxides, nitrogen oxides, particulate matter, organic matter and metals. The reduction of sulphur oxide emissions into the atmosphere using scrubber technology adds another dimension to the discussion, as this approach results in focused discharge of some pollutants to the surface water. A scoping calculation shows that an openloop scrubber on a medium-sized ship could discharge more copper and zinc daily to the surface water than the ship’s antifouling paint. The use of antifouling paint in the European Union is subject to a prior risk assessment, but scrubber discharges are not subject to any such risk assessment. This situation presents a problem from the perspective of the Marine Strategy Framework Directive, as environmental monitoring programmes in some coastal areas of the Baltic Sea have shown that levels of both copper and zinc exceed environmental quality standards. To fulfil the Marine Strategy Framework Directive requirements and achieve Good Environmental Status, having knowledge of the magnitude of different anthropogenic pressures is important. Metal inputs from open-loop scrubbers have been largely neglected until now: some metals have the potential to serve as tracers for monitoring scrubber discharges.
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